Abdominal Hernia - The Various Types and Classifications

Hernias are commoner in males than in females, though they occur at all ages and in both sexes. The term refers to abdominal hernia except where it has been distinguished as diaphragmatic or pelvic.

Definition: It is defined as the protrusion of a small sac of peritoneum into and through the wall of the abdominal cavity. Or it is simply the protrusion of any part of the internal organs through the structures enclosing them.

Classification
Hernia is classified as congenital or acquired.
1. Congenital: This is as a result of the presence of a defect in the abdominal wall or failure of closure of the umbilicus at birth.

2. Acquired: This kind of hernia develops later in life. It is usually due to defect in the abdominal wall brought about by the weakening of the supporting structure as a result of excessive strain on the abdominal wall, surgery or other factors.

Types
Types of hernia are usually identified by the anatomical site of weakness. Types of hernia therefore include:
i. Inguinal: This is the protrusion of the intestine through the inguinal ring into the inguinal canal. They are either congenital or acquired. They are usually more common in males.

Inguinal hernias are either direct or indirect based on their anatomical relationship to the inguinal canal and the direction of penetration. Direct inguinal hernia does not share the coverings of the spermatic cord but passes into a direct subcutaneous location. It is due to defects of the inferior medial areas of the inguinal floor.

Indirect inguinal or oblique hernia on the other hand is the protrusion of the abdominal organs beyond the superficial ring and into the scrotum. They share the coverings of the spermatic cord.

ii. Umbilical: It is the protrusion of the intestines through the umbilical ring. This is due to failure of the umbilical ring to close spontaneously (closure is usually around 2 years of age). This is therefore is an example of congenital hernia.

iii. Femoral: This is the protrusion of a loop of intestine through the femoral canal and exits through the femoral ring (the femoral canal is the opening beneath the inguinal ligament through which the femoral artery passes from the abdomen to the thigh). Femoral hernia is commoner in females.

iv. Ventral or Incisional: This occurs mostly in the abdominal wall. The hernia occurs most often at site of an old wound with poor or incomplete healing. It may occur as a result of infection of operation wound.

The course of Abdominal Hernia
The hernia sac may contain viscera, loop of intestine, omentum, or it may be empty.
1. Reducible: When the contents of the sac can be returned to its normal position by manipulative measures or replaced in the abdominal cavity, the hernia is said to be reducible. The content may also move back into their original position when the patient lies down.

2. Irreducible or Incarcerated: This type cannot be manipulated back into its original position. It is tightly held in place by adhesions.

3. Strangulated: is the type where the neck of the sac is constricted thereby cutting off blood supply to the contents. The constriction of the blood vessels may lead to gangrene of the viscus.